1. Field of the Invention
Caliciviruses are reported as an important cause of illness in cats. A wide variety of symptoms are observed such as fever, rhinitis, sneezing, mild conjunctivitis, occular discharge, vesicles in the external nares, oral mucosa or on the tongue, pneumonia, tracheal bronchitis, diarrhea, muscle soreness, stiff gate, and hyperesthesia. It should be noted that such signs, although reportedly common in natural cases, are not always prominent in experimental infections. It would appear that various field strains of feline calicivirus (FCV) either differ in their disease causing potential or that concurrent infection with other agents influences the disease symptoms.
Feline calicivirus strains have been identified as either neutralized by most antiserum or elicit antibodies that neutralize most other strains. One such strain, FCV-F9 is neutralized by antisera to many of the fourteen field isolates that were tested and FCV-F9 antiserum in turn neutralized all fourteen strains. For this reason, FCV-F9 was proposed as a reference strain. While the vaccines from FCV-F9 and other commercially available vaccines provide protection from most field isolates, it is not true that these vaccines prevent infection from all strains. There is, therefore, continued interest in developing a vaccine, which by itself or in combination with other vaccines would provide the desired protection upon vaccination of a cat.
2. Description of the Prior Art
U.S. Pat. No. 4,264,587 describes a vaccine for feline leukemia viremia. Kalunda et al. AJVR (1975) 36:353-356 describes the properties of the strain FCV-F9 as a vaccine. See also Bittle, et al., Ibid. (1976) 37:275-278. The strain FCV-M8 and its use as a vaccine is described by Davis and Beckenhauer, VM/SAC (1976) 71:1405-1410. The strain FCV-255 is described by Povey et al., JAVMA (1980) 177:347-350 (This particular strain is not designated in the reference.)